1. Field of the Invention
The present invention relates to a light source having a light-emitting tube including a light-emitting portion that emits light by electric discharge between electrodes and sealing portions provided on both sides of the light-emitting portion and a reflector that irradiates the light beam emitted by the light-emitting tube after aligning in a predetermined direction, and a projector having the light source.
2. Description of Related Art
Projectors that modulate a light beam irradiated by a light source in accordance with image information to project an optical image in an enlarged manner have been conventionally used for presentation purpose at conferences etc. On the other hand, such projectors are also used for home-theater purpose in response to increasing demand for watching movies etc. on a wide screen at home.
Light sources used for such projectors have a lamp housing accommodating a reflector and a discharge light-emitting tube such as a metal halide lamp and a high-pressure mercury lamp so that the light source can be attached to and detached from the projectors together with the lamp housing for the convenience of exchanging the light-emitting tube when the light-emitting tube fails to light or is exploded.
Since the light source is exchanged by users of the projectors, the light source is constructed in an explosion-proof manner where light-emitting opening of a reflector in which a light-emitting tube is disposed is covered with a transparent plate such as glass so that broken pieces of exploded light-emitting tube are not scattered around when the light source is detached from the projector.
On the other hand, since the light-emitting tube generates heat together with light, cooling air is preferably blown to cool the light-emitting tube in order to lengthen the life of the light-emitting tube.
A light source having both of the explosion-proof construction and the cooling mechanism has been known, where a pair of cooling-air-introducing openings are formed on the light-emitting opening of a reflector symmetrically around the light-emitting tube (see Japanese Patent Laid-Open Publication No. 2002-107823 [0047], [0048], FIG. 7).
The light source has a lid on the lamp housing for opening/closing the opening of the reflector. The lid is opened when the light source is attached to the projector to allow the cooling air to be introduced. On the other hand, when the light-emitting tube is exploded and the light source is detached from the projector for exchanging the light source, the lid shuts the opening of the reflector to prevent the broken pieces from scattering to the outside.
However, according to the light source disclosed in the Japanese Patent Laid-Open Publication No. 2002-107823, since the lid has to be provided on the lamp housing and a biasing member such as a helical spring is necessary for opening/closing the lid in attaching/detaching the light source to/from the projector, so that the number of components of the light source is increased to deteriorate the efficiency of the assembly work and production cost is increased in accordance with the increase in the number of the components. Further, when the light source is attached to the projector, since the lid is opened, some broken pieces may be scattered inside the projector.